21355425440 has 192 divisors, whose sum is σ = 54275235840. Its totient is φ = 7916590080.

The previous prime is 21355425419. The next prime is 21355425461. The reversal of 21355425440 is 4452455312.

It is an interprime number because it is at equal distance from previous prime (21355425419) and next prime (21355425461).

It is a self number, because there is not a number n which added to its sum of digits gives 21355425440.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 35181617 + ... + 35182223.

It is an arithmetic number, because the mean of its divisors is an integer number (282683520).

Almost surely, 2^21355425440 is an apocalyptic number.

21355425440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21355425440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27137617920).

21355425440 is an abundant number, since it is smaller than the sum of its proper divisors (32919810400).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21355425440 is a wasteful number, since it uses less digits than its factorization.

21355425440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 875 (or 867 counting only the distinct ones).

The product of its (nonzero) digits is 96000, while the sum is 35.

The spelling of 21355425440 in words is "twenty-one billion, three hundred fifty-five million, four hundred twenty-five thousand, four hundred forty".